Amplifier



March 17, 1925.

E. HEN NELLY AMPLIFIER Filed June 26, 1922 Pig. 2.

H540 STRENGTH ZN .,r Q. w 0 t T A s w m 2 av. wb d E Patented Mar. 17, 1925. i

UNITED STATES PATENT OFFICE.

EDWARD r. HENNELLY, or SCHENECTADY, NEW Yonx, AssmNon r GENERAL ELEC- rmo COMPANY, A CORPORATION or NEW YORK.

Q AMPLIFIER.

Application filed J1me 23, 1922. Serial No. 579,966. i

in a paper entitled The magnetron by Albert W. Hull, publishedin the September, 1921. number of the Journal of the Amerigan Institute of Electrical Engineers, page 15.

Theobject of my invention is to provide means whereby't'he' degree of amplification which may be- Obtained with devicesof the magnetron type may be greatly. increased.

By the term magnetron a'sused in this specification and the claims which follow, I intend to designate a device utilizing an'electron stream thefiow of which is controlled by means of a magnetic field.

The novel-features which I believe to be characteristic of my invention are set forth with particularity. in the appended claims. My invention itself, however,' both as to its organization and method of operation will best be understood by reference to .the fol.- lowing description taken in connection with,

the accompanying drawing, in which Fig. 1 shows diagrammatically a circuit arrangement whereby my invention may be earned into efi'ect, and-Figs. 2 and3 are characteristic curves illustrating the relation between the magnetic field strength and the current in a magnetron.

As illustrated in Fig. 1, the magnetron comprises an evacuated receptacle 1, containing the filamentarycathode 2 which is surrounded by a cylindrical anode 3. The source of current 4 provides heating current for the cathode. A polarizing field for the magnetron may be provided by means of coil 5 surrounding the rece tacle 1 which is supplied with current of t e proper value for producing a magnetizing field of the desired strength from a source of current 6.

Currents which are to be amplified may also be supplied to the coil 5 from the secondary 7. of the transformer, primary 8 of which is connected with the source of current to be ampllfied. The output circuit'of the magor to additional amplifiers by means of the I secondary winding 11. The output circuit of the magnetron also includes the coil 12 which surrounds the receptacle 1.

Inthe operation ot' the system described the coil' 12 is so wound that the magnetic field produced thereby opposes the polarizing magnetic field produced by the coil 5. The curve of Fig.2 is a typical characteristic curve showing the relation between magnetic field strength and current in the magnetron. The degree of amplification which may be obtained depends upon the slope of the vertical part of this curve. In the.no'r mal op ei'ation of the magnetron as an amplifier the polarizingfield winding is made of sufiicient strength to hold the current --through the magnetron at some value, as,,

for example, the value indicated by the point When the additional magnetic A on the curvealong the vertical portion of the curve.

field. supplied by the current in the output circuit as illustrated and described is proform shown in Fig. 3; that is, the slope of the vertical part of the curve-will be made vided, the characteristic curve will take the much steeper and the degree of amplification I which may be obtained will therefore be much greater. In this easethe value of the polarizing field required to maintain the value of the magnetron current at the point A will be slightly larger, other factors being equal, than in the case illustrated in Fig. 2,. this difference being equal to the strength of the field furnished by the coils 12. In the case illustrated in Fig. 3, an increase in the field produced by coil 5 will produce aconsequent decrease'in the magnetron current.

and this in turn will cause a decrease in the further decrease of the magnetron current. The result of this conjoint action of the fields produced in coils 5 and 12 results'in the steepening of the characteristic curve as indicated in Fig. 3.

While I have shown and described the field produced by coil 12 which will result in 1 simplest embodiment of my invention, it will be apparent that many modifications in the circuit arrangements as well as in the form of magnetron employed maybe made with out departing from the scope of my invention set forth in the appended claims.

lVhat I claim as. new and desire to secure by Letters Patent of the United States, is 1. In an amplifying system, a magnetron having means for producing a polarizing magnetic field. input and output circuits and a coil in said output circuit connected in such a way that it produces a magnetizing field \i'h ich' normally opposes the polarizing magnetic field.

2. In an amplifyingsystem. a magnetron having means for producing a polarizing magnetic field. input and output circuits and a coil in said outputcircuit connected in such a way that it produces a n'iagnetizing field which normally opposes the polarizing magnetic field and which varies in accordance with variations in current supplied to "field int e magnetron and ,producing by means of current in the output circuit a magnetic field which opposes the polarizing magnetic field.

4. The method of operating a magnetron having input andoutput circuits which consists in' producing a polarizing magnetic field in the magnetron, supplying a current to he amplified to the input circuit and producing by means of current in the output circuit a magnetic field which opposes the polarizing field and which varies in accordance with variations in the current supplied to the input circuit.

In witness whereof. I have hereunto set my hand this23rd day of June, 1922.

EDWARD F. HENNELLY.- 

